George,
Firstly, I think you are coming down unnecessarily hard on Mark who IMHO has passed along a valuable and encouraging bit of information. If you were both an experienced machinist AND a Stuart stockist, as I was during the 1990s-2000s, you might have a better understanding of the circumstances and that there were and are sufficient reasons for criticism.
The "old" Stuarts (Henley) poured their castings in large batches of one selected casting, for instance 100s of #9 cylinder castings, 100s of #10 flywheels, etc, and all went into bins from which castings for sets or to supply a one-off replacement were pulled. The efficiency and economy of this approach certainly might be debated, and in the end of course it didn't survive, but replacement castings were always quickly and easily available. That spoiled us I suppose.
Jones & Bradburn, on the other hand, took the opposite approach. They tooled up to produce castings automatically in full sets which left very few, if any, orphaned castings to lay about gathering dust. While they claimed replacement castings were readily available, my personal experience was that unless I was extremely lucky, they were not.
My personal experience with Stuart Models (under Jones & Bradburn) could not have been more pleasant. They were always responsive and helpful, however the reality of delivery of anything other than a complete engine set was something else. I once ordered the beam alone for the Major Beam engine and when it had not been shipped after over 14 months I gave up. This was not down to unwillingness or indifference on the part of the staff or any one person but was the result of their manufacturing process which made loose parts a rarity if not non-existent.
The new situation appears, for the moment, to be an improvement but the question I must ask myself is, if the castings quality had declined under J&B, and the new owners are old founders, what promise is there that the castings will improve? IMHO, the reasons for the decline in castings quality, specifically the machinability, is that in the process of automating the manufacture of the castings J&B "value-engineered" the patterns to remove as much metal as possible, including minimizing machining allowances, yet still retain full appearance and function. In doing so many castings were thinned to the point that chilling and other flaws were inevitable. I could be wrong about this, but that's my assessment, from a long distance away.